Mj. Brown et al., SHAPED PULSES FOR SELECTIVE INVERSION IN SOLID-STATE DEUTERON NMR-SPECTROSCOPY, Journal of magnetic resonance. Series A, 122(2), 1996, pp. 165-178
Double sideband modulation and pulse shaping can be combined to improv
e the performance of selective pulses in solid-state deuteron NMR. Eff
icient off-resonance selective inversion of deuterons requires simulta
neous irradiation of both spin-1 transitions, i.e., at symmetric offse
ts from the Larmor frequency (nu(0) +/- Delta). This is best accomplis
hed with double-sideband-modulated pulses. Frequency-selective profile
s can be improved by shaping the RF pulses. A variety of commonly used
selective pulse shapes are evaluated for their applicability to solid
-state deuteron powder patterns. A new pulse shape is introduced; the
squared isosceles triangle, Generally, pulses with low bandwidth-durat
ion product, such as the Gaussian envelope, are found to be the most e
ffective for selective inversion in solid-state H-2 NMR, This is a con
sequence of the large inhomogeneous quadrupolar interaction and fast,
anisotropic spin-spin relaxation. (C) 1996 Academic Press, Inc.